Preparation of cycloolefins

ABSTRACT

THERE IS DISCLOSED A METHOD COMPRISING THE PREPARATION OF CYCLIC OLEFINS AND CYCLIC DIOLEFINS CHARACTERIZED IN THAT OPEN CHAIN DIOLEFINS ARE HATED IN THE PROCESS OF A HOMOGENEOUS CATALYST.

United States Patent 6 3,631,209 PREPARATION OF CYCLOOLEFINS Kenneth J.Frech, Tallmadge, and David A. Hutchings and Frederic H. Hoppstock,Akron, Ohio, assignors to The Goodyear Tire & Rubber Company, Akron,Ohio N Drawing. Filed June 22, 1970, Ser. No. 48,461 Int. Cl. C07c /20U.S. Cl. 260--666 A 8 Claims ABSTRACT OF THE DISCLOSURE There isdisclosed a method comprising the preparation of cyclic olefins andcyclic diolefins characterized in that open chain diolefins are heatedin the process of a homogeneous catalyst.

This invention is directed to the preparation of cycloolefins from openchain conjugated diolefins. More particularly, it is directed to thepreparation of cyclopentene and cyclopentadiene from 1,3-pentadiene andmethyl substituted cyclopentadiene and methyl substituted cyclopentenesfrom methyl substituted 1,3-pentadienes and methyl substitutedcyclopentenes and methyl substituted cyclopentadienes andcyclohexadienes from open chain conjugated hexadienes, such as1,3-hexadiene and 2,4- hexadiene.

Cycloolefins and cyclo diolefins are presently obtained in limitedquantities as by-products as naphtha and gas oil cracking. The naphthaand gas oil crackers are operated in a manner to produce maximum amountsof ethylene and other cycloolefins. Therefore, only limited quantitiesof cycloolefin and cyclo diolefin are available for use as startingmaterials to prepare other products such as resins, insecticides and thelike.

It is an object of this invention to significantly enlarge the supply ofcyclic olefins and cyclic diolefins by the utilization of open chaindiolefins which are also found as by-products in various refineryoperations. For instance, 1,3-pentadiene and methyl substituted1,3-pentadiene which are not now utilized, could be employed to producemore valuable products. Also, 1,3- and 2,4-hexadiene could be utilizedin accordance with this invention to produce more valuable methylsubstituted cyclopentadiene and cyclohexadienes.

The preparation of cyclopentadienes from 1,3-pentadienes is known. Forinstance, in U.S. Pat. 2,438,398 there is described the process for theproduction of cyclopentadiene from 1,3-pentadiene by dehydrogenation at300 C. to 700 C. at from 10 to 1000 millimeters of pressure. In U.S.Pat. 2,438,399 there is described a process for the production ofcyclopentadiene from 1,3-pentadiene by the dehydrogenation in thepresence of activated silica gel at 450 C. to 600 C. at 10 to 200millimeters of pressure. In U.S. Pat. 2,438,400 there is described that1,3- pentadiene in pure form or admixed with normal pentane and normalpentene can be converted to 1,3-cyclopentadiene on contact with acatalyst such as CR O on alumina at 400 C. to 700 C. at 10 to 100millimeters of pressure. In U.S. Pat. 2,438,401 is described a processfor the production of cyclopentadiene-1,3 by contact of 1,3- pentadienewith SiC at 450 C. to 650 C. and 10 to 200 millimeters of pressure. InU.S. Pat. 2,438,402 is described the cyclization of 1,3-pentadiene toform 1,3- cyclopentadiene by bringing 1,3-pentadiene into contact withfused alumina at 400 C. to 700 C. at 10 to 200 millimeters of pressure.In U.S. Pat. 2,438,403 cyclopentadiene is derived from 1,3-pentadiene bycontact with sub-divided iron or steel at 450 C. to 650 C. and atpressures from 10 to 200 millimeters.

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These prior art processes, however, either were trulythermo-dehydrogenation processes or were processes which employed fixedbed catalyst systems such as the activated silica gel, the chromiumoxide on alumina or the silica carbide or fused alumina or sub-dividediron or steel. In contrast to these prior art processes, the presentinvention uses a homogeneous catalyst system.

Therefore, according to the present invention, cyclic olefins and cyclicdiolefins are prepared from open-chain diolefins by heating in thepresence of homogeneous catalysts.

All that is required to perform the present invention is to pass theopen-chain diolefin, for instance, 1,3-pentadiene and the homogeneouscatalyst system, through a tubular reactor heated to the desiredtemperature. Among the open-chain diolefins which are useful as thereactants in this invention are 1,3-pentadiene from which can be formedcyclopentene and cyclopentadiene; 4-methyl-l,3- pentadiene from whichcan be formed a methyl substituted cyclopentene and a methyl substitutedcyclopentadiene; 2- methyl-l,3-pentadiene may be employed from which canbe obtained methyl substituted cyclopentadiene and cyclopentene;3-methyl-l,3-pentadiene may be employed and methyl-substitutedcyclopentenes and methyl substituted cyclopentadienes are obtained.Also, there may be employed 1,3- and 2,4hexadienes from which there canbe obtained methyl-substituted cyclopentene, methyl substitutedcyclopentadienes and cyclohexadienes.

The catalyst employed in this invention can be a variety of catalystswhich are homogeneous in nature. Representative of the catalysts whichcan be employed in this invention are: methyl mercaptan, ethylmercaptan, ammonium sulfide, ammonium hydrosulfide, hydrogen bromide,ammonium bromide, dibromo methane, bromo chloro methane, allyl bromide,bromine, hydrogen iodide, iodo methane, iodine, ammonium iodide, carbondisulfide, dimethyldisulfide and carbonyl sulfide. One of the morepreferred homogeneous catalyst is hydrogen sulfide.

The temperature employed in the process of this invention can range fromabout 450 C. to about 1000 C. with a more preferred range of about 550C. to about 800 C. and still more preferred range of about 575 C. to 750C. The process can be employed with the reactants in the pure state or adiluent may be employed. It is usually desirable to employ a diluent forheat transfer purposes. Among the diluents which might be mentioned assuitable are steam, nitrogen, methane, ethane, pentane, and otherhydrocarbon gases or inert gases which are stable under the conditionsto be employed. The diluent to open chain diolefin mole ratio may varyover a very Wide range; that is, from 0 to 25/1.

The residence time at which the open chain diolefin is heated is notcritical and may vary from a low of 0.01 second up to 1 minute with amore preferred time being from 0.25 second to 10 seconds and a stillmore preferred range would be from 0.75 second to 5 seconds.

The amount of catalyst required in the process of this invention has notbeen found to be too critical except that, of course, a catalytic amountmust be employed. For instance, good results have been obtained when aslittle catalyst as 0.1 mole percent up to 200 mole percent based on themoles of the open-chain diolefin as the reactant. However, a morepreferred range is from about 10 mole percent to about 100 mole percentwith the most preferred being from about 15 mole percent to about molepercent.

The practice of this invention is illustrated by the followingexperiments which are to be interpreted as representative rather thanrestrictive of the scope of this invention. The conditions and resultsof the experiments are set forth in table form.

3 EXAMPLE 1 In this series of experiments, piperylene or 1,3-pentadienewas converted into cyclopentene and cyclopentadiene using hydrogensulfide as the homogeneous catalyst. In these experiments, no diluentwas employed. In certain of the runs in each series no homogeneouscatalyst is employed and these runs are considered controls. In thesecontrol experiments the hydrogen sulfide was replaced With an equivalentmolar amount of nitrogen. The operating conditions and the results arereported in the table below in which column 1 is the run number, column2 is the mole percent of hydrogen sulfide based on the piperylene,column 3 is the temperature in degrees centigrade, column 4 is theresidence time in seconds, column 5 is the cyclopentene yield in molepercent, column 6 is the cyclopentadiene yield in mole percent, column 7is the reaction selectivity to cyclic unsaturated products includingboth cyclopentene and cyclopentadiene in percent, and column 8 is thepiperylene in mole percent.

These examples were performed in a vertically mounted reactor assemblyconsisting of a 10-inch length of inch OD, and .300 inch IDstainless-steel tubing. The reactor was heated in a tubular electricalresistance furnace with asbestos insulation plugs on either end. Thetemperature was measured by conventional reactor skin thermocouples. Thetemperature was controlled with an ECS temperature controller which useda reactor skin thermocouple as a temperature sensor. When the desiredtemperature had been reached, the reactants were fed into the reactor ata rate to give the desired residence time. Piperylene was introducedusing a Harvard syringe pump, while gases were metered throughrotameters. Samples of the reactor efiluent were taken using a gas-tightsyringe and immediately injected into an analytical gas chromatograph.This rapid sampling technique was required because of the propensity ofcyclopentadiene to dimerize.

chromatograph where reactant and products are resolved TABLE 2 Productcomposition, mole percent Cyclo- Cyclo- Homogeneous catalyst pentadienepentene Hydrogen sulflde 44 5 Bromochloromethane 32 2 Allylbrornldc 4O 9Hydrogen iodide. 21 Carbon disulfide 15 8 No promoter 10. 3 2. 5

The results set forth in the table above indicate that the varioushomogeneous catalysts employed produced results strikingly improved overthe truly thermal convention of piperylene to cyclic olefins.

EXAMPLE III In these experiments in which piperylene is converted tocyclopentene and cyclopentadiene a variety of homogeneous catalysts wereemployed. These experiments were conducted in the vertically mountedreactor that was employed in Example I. The operating procedure wassimilar TABLE 1 HgS concen- Yield, mole percent tration, mole Res.Reaction Piperylene percent on Tcmp., time, Cycloselee., conv.piperylene C. see. pentene CPD percent percent As can be seen from theresults set forth in the table above, when piperylene is heated in thepresence of hydrogen sulfide, a very large increase in the percent yieldof cyclopentene and cyclopentadiene is obtained as well as a vastimprovement in reaction selectivity to cyclic olefins.

EXAMPLE II In these experiments, piperylene is converted to cyclicolefins by the use of various homogeneous catalysts as indicated in thetable below. The residence time in these experiments was 0.8 second, thetemperature employed was 650 C. and helium at a mole ratio ofhelium/piperylene of 2/1 was employed as a diluent.

These examples were performed in a pulse reactor system consisting of amirco .250 inch OD stainless steel reactor placed in series with thehelium carrier stream of a gas chromatograph. Samples are injected intothe helium line and pass through the reactor and into the gas to that ofExample I except several other homogeneous catalysts were employed otherthan hydrogen sulfide. In certain of the runs, such as 4, 6 and 16, nocatalysts were employed and are considered controls. Again, as inExperiment 1, the quantity of the catalyst was replaced with nitrogen.In one experiment, No. 16, a diluent was employed which was steam, in amole ratio of 5/1 steam/ piperylene.

The results are given in the table below in which column 1 is the runnumber, column 2 is the catalyst and the amount of catalyst employedreported in mole percent based on the piperylene charged, column 3 isthe temperature in degrees centigrade, column 4 is the residence time inseconds, column 5 is the yield in mole percent of cyclopentadieneobtained, column 6 is the mole percent of cyclopentadiene obtained,column 7 is the reaction selectivity in percent of cyclic olefinsobtained and column 8 is the piperylene converted, represented in molepercent.

TABLE 3 Piper- Yield mole percent Reaction ylene Mole Res. selecconv.,

percent on Temp., time, Cyclotivity, mole Run No. Catalyst piperylene 0.sec pentene CPD percent percent 1 CHzBr; 5.0 550 9. 6 18. 2 1. 35.0 54.9 2 550 12. 1 21. 9 1. 6 37. 62. 5 600 2. 7 16. 4 7. 3 50. 0 47. 2

While certain representative embodiments and details have been shown forthe purpose of illustrating the invention, it will be apparent to thoseskilled in this art that various changes and modifications may be madetherein without departing from the spirit or scope of the invention.

What is claimed is:

1. The method of preparing cyclic olefins and cyclic diolefinscomprising heating at least one acyclic diolefin from the groupconsisting of acyclic pentadienes, methyl substituted acyclicpentadienes and acyclic hexadienes to temperatures ranging from about550 C. to about 800 C., while said acyclic diolefins are in contact withthe homogeneous catalyst selected from the group consisting of hydrogensulfide, methyl mercaptan, ethyl mercaptan, ammonium sulfide, ammoniumhydrosulfide, hydrogen bromide, ammonium bromide, dibromo methane, bromochloro methane, allyl bromide, bromine, hydrogen iodide, iodo methane,iodine, ammonium iodide, carbon disulfide, dimethyl-disulfide andcarbonyl sulfide.

2. The method according to claim 1 in which the acyclic diolefin is1,3-pentadiene.

3. The method according to claim 1 in which the acyclic diolefin is4-methyl-1,3-pentadiene.

References Cited UNITED STATES PATENTS 3,403,192 9/1968 Vadekar et al.260-666 A 3,449,458 6/ 1969 Tiedje et al. 260666 A 3,373,213 3/1968Pasternak et al. 260666 A 2,890,253 6/1959 Mullineaux et al. 260666 A3,272,877 9/1966 Franz et al. 260-666 A 3,116,338 12/1963 Guest et a1260666 A DELBERT E. GANTZ, Primary Examiner V. OKEEFE, AssistantExaminer

